This invention relates to epoxy/polyester/polycarbonate compositions, and more specifically, to such compositions for adhesive applications.
It is known to prepare one-component adhesives for applications wherein the adhesive is cured at an elevated temperature such as, for example, above about 100.degree. C. Such adhesive compositions are particularly useful in manufacturing processes wherein the apparatus to be assembled is to be also painted and sent though a paint oven, such as in the manufacture of automobiles, appliances, and office furniture, or in manufacturing applications wherein the assembly process permits a separate heat-cure step inorder to achieve higher adhesive strength, such as in the manufacture of aircraft. Such compositions typically comprise a curing agent which is solid at ambient temperatures, dispersed in a resin which is liquid at ambient temperatures. Examples of such compositions include those comprising solid polyamines dispersed in liquid epoxy resins, and solid polyisocyanates dispersed in liquid polyols. Such compositions are typically applied as an adhesive to a substrate to be bonded and sheated to a temperature high enough to melt the curing agent sufficiently to allow it to quickly cure the liquid resin.
However, such compositions are not storage stable at ambient temperatures. Under storage conditions, the solid/liquid components of such compositions will still be able to react to a limited degree and cure the composition over time.
It is also known to prepare compositions comprising epoxy resins, aromatic polyesters or aromatic polycarbonates, and particular catalysts, as described, for example, in U.S. Pat. No. 5,037,903. Such compositions are taught in this patent to be useful for preparing thermoformed articles and as the matrix material for polymeric composites. However, such compositions are typically too brittle at ambient temperatures for application as an adhesive.
It would be desirable to provide an adhesive composition which is suitable for application as an adhesive at ambient temperatures, yet which has a long storage life.